1. Field of the Invention
The present invention relates to a color adjusting method for a projector, and in particular, to a color adjusting method used if the color of a screen or wall used as an image projecting surface is different from white, to adjust properly the colors of an image displayed on the projecting surface.
2. Description of the Related Prior Art
An image projected by a projector such as a liquid crystal projector is displayed on a projecting surface. The projecting surface is generally composed of a screen or a wall. Such a screen or wall is not necessarily white. Even if it is white when it starts to be used, it may become yellowish or bluish later. The image projected on such a screen or wall is displayed in colors relatively different from actual ones. Consequently, a user does not see the displayed image in its original colors. To allow the user to see the image in its original colors, the colors of the projected image must be adjusted.
FIG. 1 is a view showing a conventional color adjusting method. A projector 10 projects an image on a screen 20. A user M observes a displayed image 30 on the screen 20. On the basis of the results of the observation, the user adjusts colors by operating the projector 10.
FIG. 2 is a block diagram showing a configuration of the projector 10. The projector 10 includes an operating section 11, a color correction processing section 12, an output signal processing section 13, and a video output section 14. The operating section 11 includes key switches and the like and is operated on the basis of the user M's determinations. On the basis of the user M's operation of the operating section 11, the color correction processing section 12 generates correction data d used to correct an externally supplied video signal in. The output signal processing section 13 adds the correction data d to the video signal into generate a color-adjusted video signal P. The video output section 14 is, for example, a three-plate type liquid crystal projector unit that splits white light generated by a light source into primary lights in red, green, and blue. The video output section 14 then modulates the primary lights in accordance with the video signal P. Subsequently, the video output section 14 carries out additive color mixture and then projects the mixed light on the screen 20.
With the color adjusting method used for the projector 10, if the color of the screen 20 is different from white, the user M first observes the color of the displayed image 30. On the basis of the results of the observation, the user operates the operating section 11 to carry out white balance adjustment, color temperature adjustment, and color corrections (adjustment of luminance, hue, or saturation) so that the image assumes desired colors.
However, with this conventional color adjusting method, the user M observes the colors of the projected image 30 and subjectively adjusts them on the basis of the results of the observation. Thus, the colors are adjusted without using any accurate references. Therefore, the user M disadvantageously cannot adjust the colors accurately.